1. Field of the Invention
This invention relates to decay resistant sheet material and more particularly to such materials adapted for use in shoe construction.
2. Description of the Prior Art
For purposes of economy, it has been the practice to employ synthetic sheet material in the manufacture of shoes. Such "shoeboard" as it has come to be known, comprises a disposition of an elastomeric binder and particularly a neoprene or styrene-butadiene elastomer in a fibrous matrix and is currently in fairly extensive use in counters and shoe insoles. For durability, especially where the shoeboard is employed in tropical climates, the board must be treated with a substance which provides the board with resistance to decay by fungus and other microbial organisms, a property not naturally possessed by leather and other shoe construction constituents unless treated chemically.
Metallic quinolinolates, particularly copper-quinolinolate effectively render some cellulosic materials resistant to fungus and bacteria. However, due to environmental and economic considerations they have not been successfully employed as a preservative or fungicide in shoeboard due to difficulty in processing and retention within the shoe materials over an extended period of time. In addition, it has been found that metallic quinolinolates degrade the flexural property of the shoeboard over time when used in combination with neoprene or styrene-butadiene binders.
Prior art attempts to incorporate the metallic quinolinolates in a cellulosic sheet have proved less than satisfactory. For example, incorporation of the powdered form of the metallic quinolinolate by adding it to the paper slurry before deposition on the wire has proved ineffective due to low retention causing an effluent from the papermaking process which contains unacceptably high levels of metallic quinolinolates. Further, it is unacceptable to lose these amounts of metallic quinolinolates since they are expensive and it is desirable to have effective utilization of the quinolinolate. Further, size press application of a solubilized form of the copper-quinolinolate is also ineffective due to the leachability of the same by water.
Methods such as those disclosed in U.S. Pat. No. 3,493,464 to Bowers et al. and U.S. Pat. No. 3,713,963 to Hager demonstrate retention rates of approximately 70% of the theoretical by formation of the metallic quinolinolate in the pulper by the proper addition of the required compounds and precipitation thereof, in situ, of the insoluble salt. However, methods are also suggested to treat the paper machine effluent in order to remove the remaining quinolinolate therefrom.
Furthermore, it has been observed that the copper-quinolinolate, being incompatible with the other popular insole binders namely, neoprene and styrene-butadiene rubber causes the coagulation of such binders, thereby severely adversely affecting the uniform saturation of the web with the binder along with the strength and resilience thereof.
Accordingly, it is an object of the present invention to provide a fungus and mold resistant synthetic sheet material which overcomes the deficiencies associated with the prior art.
It is another object of the present invention to provide a fungus and mold resistant sheet material employing a metallic quinolinolate as a fungicide.
It is another object of the present invention to provide a fungus and mold resistant sheet material of optimal strength and resilience.
It is another object of the present invention to provide a method of economically making a fungus and mold resistant sheet material with a fungicide which is retained by the sheet material at substantially maximum rates during the fabrication process. It is another object of the present invention to provide a fungus and mold resistant material which retains the fungicide therein over long periods of time.
It is another object of the present invention to provide a method of making fungus and mold resistant material wherein substantially none of metallic ions from a fungicide in the material are lost in the effluent or waste water.
These and other objects will become more readily apparent from the following summary of the invention and detailed description thereof.